URL: https://www.msha.gov/mine-data-retrieval-system

This dataset contains the annual summation of employee hours and coal production reported by mine operators where the average quarterly employment is greater than zero with grouping by calendar year, subunit code and mine ID beginning on 1/1/2000. The subunit code identifies the location or operation of the mine relating to the: (01) Underground; (02) Surface at underground; (03) Strip, quarry, open pit; (04) Auger; (05) Culm bank/refuse pile; (06) Dredge; (12) Other mining; (17) Independent shops or yards; (30) Mill operation/preparation plant; (99) Office workers at mine site.